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Use the function and its arguments from the list

I am trying to store functions and their arguments in a list, for example, in the following:

parameters <- list(a1 = list(fun = dnorm,
                             args = c(mean = 150, sd = 100)),
                   a2 = list(fun = dpois,
                             args = c(lambda = 40)))

Now I would like to use stored functions and their arguments without using eval(parse()).

Now suppose that I want to calculate functions using the following vector:

x <- 1:100

According to what I'm looking for, if I call the function stored in "a1", the results should be identical:

dnorm(x, mean = 150, sd = 100)
 [1] 0.001314684 0.001334353 0.001354181 0.001374165 0.001394306 0.001414600 0.001435046 0.001455641 0.001476385
 [10] 0.001497275 0.001518308 0.001539483 0.001560797 0.001582248 0.001603833 0.001625551 0.001647397 0.001669370
 [19] 0.001691468 0.001713686 0.001736022 0.001758474 0.001781038 0.001803712 0.001826491 0.001849373 0.001872354
 [28] 0.001895432 0.001918602 0.001941861 0.001965205 0.001988631 0.002012135 0.002035714 0.002059363 0.002083078
 [37] 0.002106856 0.002130691 0.002154582 0.002178522 0.002202508 0.002226535 0.002250599 0.002274696 0.002298821
 [46] 0.002322970 0.002347138 0.002371320 0.002395511 0.002419707 0.002443904 0.002468095 0.002492277 0.002516443
 [55] 0.002540591 0.002564713 0.002588805 0.002612863 0.002636880 0.002660852 0.002684774 0.002708640 0.002732444
 [64] 0.002756182 0.002779849 0.002803438 0.002826945 0.002850364 0.002873689 0.002896916 0.002920038 0.002943050
 [73] 0.002965948 0.002988724 0.003011374 0.003033893 0.003056274 0.003078513 0.003100603 0.003122539 0.003144317
 [82] 0.003165929 0.003187371 0.003208638 0.003229724 0.003250623 0.003271330 0.003291840 0.003312147 0.003332246
 [91] 0.003352132 0.003371799 0.003391243 0.003410458 0.003429439 0.003448180 0.003466677 0.003484925 0.003502919
[100] 0.003520653

I tried the following example:

> parameters[[1]]$fun(x, parameters[[1]]$args)
  [1]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
  [9]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [17]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [25]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [33]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [41]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [49]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00
 [57]  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00  0.000000e+00 1.097221e-314  0.000000e+00 1.506905e-282
 [65]  0.000000e+00 3.790526e-252  0.000000e+00 1.746366e-223  0.000000e+00 1.473646e-196  0.000000e+00 2.277577e-171
 [73]  0.000000e+00 6.447260e-148  0.000000e+00 3.342714e-126  0.000000e+00 3.174282e-106  0.000000e+00  5.520948e-88
 [81]  0.000000e+00  1.758750e-71  0.000000e+00  1.026163e-56  0.000000e+00  1.096607e-43  0.000000e+00  2.146384e-32
 [89]  0.000000e+00  7.694599e-23  0.000000e+00  5.052271e-15  0.000000e+00  6.075883e-09  0.000000e+00  1.338302e-04
 [97]  0.000000e+00  5.399097e-02  0.000000e+00  3.989423e-01

But this is not consistent with the results. dnorm(1:100, mean = 150, sd = 100)

The only workaround I have found so far is to use eval(parse()), but I would like to find an easier way.

Is it possible?

Thank you for your help.

Boris

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2 answers

You should slightly change parameters:

parameters <- list(a1 = list(fun = dnorm,
                             args = list(mean = 150, sd = 100)),
                   a2 = list(fun = dpois,
                             args = list(lambda = 40)))
x <- 1:100

do.call lapply :

do.call(parameters[[1]]$fun, c(list(x), parameters[[1]]$args))

lapply(parameters, 
        function(para, x) do.call(para$fun, c(list(x), para$args)), 
        x=x)
+3

. :

parameters[[1]]$fun(x, parameters[[1]]$args[1], parameters[[1]]$args[2])

dnorm .

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